Nebraska omicron cluster suggests sooner symptom onset

An investigation right into a cluster of omicron infections in Nebraska suggests the closely mutated variant has a shorter incubation interval and causes comparable or milder signs in comparison with previous variants for people who find themselves vaccinated or beforehand contaminated, based on the U.S. Facilities for Illness Management and Prevention.

The CDC on Tuesday launched findings from an epidemiological investigation into six omicron instances confirmed from a single family in Nebraska.

A 48-year-old man who returned to the U.S. on Nov. 23 from a convention in Nigeria skilled signs a day later and examined optimistic for the virus on Nov. 26. The person, who was unvaccinated and had a previous historical past of symptomatic an infection in 2020, reported he was not sporting a masks when he had shut contact with a masked particular person who was coughing on the worldwide convention on Nov. 20.

The person took an antigen take a look at earlier than returning to the U.S. and the outcomes got here again detrimental on Nov. 21. Upon his return to the U.S., he was nonetheless asymptomatic and had shut contact with 5 members of his family in Nebraska with out sporting a masks on Nov. 23.

The 5 members of his family, at the very least certainly one of whom was as younger as 11 years outdated, developed signs from Nov. 24 – 26 and subsequently examined optimistic. 4 of them had prior histories of symptomatic an infection in 2020, certainly one of whom was absolutely vaccinated with two Pfizer doses.

One other particular person within the family was unvaccinated and had by no means examined optimistic for Covid earlier than. Nevertheless, that individual did have gentle higher respiratory signs in November 2020 earlier than the opposite members of the family first received contaminated.

The CDC mentioned it took 33 to 75 hours, a median of about 3 days, for family members to point out signs after publicity to the person who travelled, suggesting a shorter incubation interval with omicron. The median incubation interval for Covid is 5 days or extra, whereas the delta variant usually takes about 4 days for signs to point out, based on the CDC.

The family members who had been reinfected skilled fewer signs in comparison with their first infections in November 2020, based on the CDC. Two of them reported fevers after an infection, none reported lack of style or scent.

The unvaccinated particular person who had not examined optimistic earlier than skilled cough, joint ache, congestion, fever and chills. No person within the family required hospitalization after testing optimistic from omicron, and none of them had underlying well being situations or compromised immune programs. These reinfected didn’t require hospitalization after their first infections in 2020 both.

The primary confirmed case of omicron was reported on Dec. 1 within the San Francisco space by California public well being authorities. The person had returned from a visit to South Africa. Nevertheless, the CDC subsequently discovered somebody who reported signs on Nov. 15 after worldwide journey, indicating that the variant may have arrived within the U.S. earlier.

Omicron was first recognized by South Africa and Botswana in November. The variant now represents 58% of sequenced instances within the U.S. whereas delta makes up about 41% of instances, based on the CDC.

A rising physique of knowledge from South Africa and the UK signifies that folks don’t get as sick from omicron in comparison with the delta variant. The U.Ok. Well being Safety Company discovered that folks contaminated with omicron had been 50 – 70% much less prone to require hospitalization. South African scientists discovered that folks contaminated with omicron had been 70% much less prone to develop extreme illness.

Nevertheless, the authors of the research cautioned towards studying too deeply into the preliminary knowledge, as a result of vaccination and immunity from prior an infection may have influenced the findings.

One other research from the U.Ok. Well being Safety Company discovered {that a} booster dose of Pfizer and BioNTech’s vaccine supplies 75% safety towards symptomatic illness from omicron. South African knowledge means that two-doses of the Pfizer vaccine nonetheless protects towards extreme sickness, however is way much less efficient at stopping omicron an infection.

Within the U.S., new Covid instances are surging to close pandemic highs. The nation reported a median of greater than 237,000 day by day new instances for the seven-day interval ending Monday, up 66% over the previous week, based on a CNBC evaluation of knowledge from Johns Hopkins College.

Greater than 70,000 individuals within the U.S. are at present hospitalized with Covid, up 3% over the previous week, based on a seven-day common of knowledge from the Well being and Human Providers Division as of Dec. 27.